Modulating the d-Band Center Enables Ultrafine Pt₃ Fe Alloy Nanoparticles for pH-Universal Hydrogen Evolution Reaction.

Abstract

By providing dual active sites to synergistically accelerate H₂ O dissociation and H⁺ reduction, ordered intermetallic alloys usually show extraordinary performance for pH-universal hydrogen evolution reaction (HER). Herein, activated N-doped mesoporous carbon spheres supported intermetallic Pt₃ Fe alloys (Pt₃ Fe/NMCS-A), as a highly-efficient electrocatalyst for pH-universal HER, are reported. The Pt₃ Fe/NMCS-A exhibits low overpotentials (η₁₀ ) of 13, 29, and 48 mV to deliver 10 mA cm^-2 in 0.5 m H₂ SO₄ , 1.0 m KOH, and 1.0 m phosphate buffered solution (PBS), respectively, as well as robust stability to maintain the overall catalytic performances. Theoretical studies reveal that the strong Pt 5d-Fe 3d orbital electronic interactions negatively shift the d-band center (ε_d ) of Pt 5d orbital, resulting in reduced H* adsorption energy of Pt sites and enhanced acidic HER activity. With Pt and Fe acting as co-adsorption sites for H* and *OH intermediates, respectively, a low energy barrier is required for Pt₃ Fe/NMCS-A to dissociate H₂ O to afford H* intermediates, which greatly promotes the H* adsorption and H₂ formation in alkaline and neutral conditions. The synthetic strategy is further extended to the synthesis of Pt₃ Co and Pt₃ Ni alloys with excellent HER activity in pH-universal electrolytes, demonstrating the great potential of these Pt-based alloys for practical applications.